Tifernine Dunes (image left, July 1995) The Tassili N’ Ajjer of southeastern
Algeria consists of large areas of sand dunes and substantial areas of sandstone
bedrock outcrops. This photograph (NASA) vividly displays the differences
between these two major landforms. The orange, complex, linear Tifernine Dunes
with superimposed star dunes were named for the intermittently-flowing,
south-to-north Tifernine watercourse along the southwestern extent of the dunes.
This very distinctive alignment of sand dunes provides Space Shuttle astronauts
a land reference in the much larger Sahara Desert. The dark, weathered sandstone
rocks that border the Tifernine Dunes to the east and southwest have deep,
narrow ravines that comprise a well-entrenched drainage pattern through the
higher elevations of the plateau southwest of the dune field. This erosion
process began millions of years ago when the climate was much wetter. This
region now receives less than 2.5 cm of rainfall annually.